Papermaking machine

ABSTRACT

Machine for a web having at least one marking device structured and arranged to apply at least two markings at a distance from one another in a longitudinal direction to the web. At least one measuring device is arranged downstream, relative to a web run direction, of the at least one marking device. The at least one measuring device is structured and arranged to measure the distance between the markings. The instant abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119 of GermanPatent Application No. 10 2004 018 522.0, filed on Apr. 14, 2004, thedisclosure of which is expressly incorporated by reference herein in itsentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a machine for producing a paper, board,tissue or another fibrous web from a fibrous stock suspension or forfinishing or further processing the fibrous web.

2. Discussion of Background Information

Problems may occur to the web dimensions during the production,processing and finishing (or further treatment such as during a printingprocess) of fibrous webs. For example, a change in length of the web asa result of web tension or as a result of stretching of the web. Theseeffects to the web dimensions may occur because of the pressuretreatment, the thermal treatment or as a result of a changing moisturecontent. It is therefore necessary to measure the stretching of the web.WO 99/22067 discloses an example of a papermaking machine for producinga paper web from a fibrous stock suspension.

Accordingly, the prior art teaches measurements of this type are carriedout indirectly by comparing the drive speeds within a machine or via ananalysis of the winding hardness of a reel produced from the fibrous webin a winding machine. A method of this type has the disadvantage that itdoes not permit any information to be obtained about stretch within theproduction process. In particular, a change of this type occurs duringthe change from one machine to another machine in which the fibrous webis processed further “offline”. For example, when the fibrous web isfirst wound onto a reel during its production from the fibrous stocksuspension. The reel which is stored temporarily and cut into aplurality of rolls of a desired width is directed to slitting devices ina subsequent operation. It is possible, the fibrous web is stored on areel that is coated with a medium in a coating machine at a later time.

When the stretch is measured conventionally, slippage of the fibrous webwith respect to the surfaces of the driving rolls distorts theinformation from the drive signals. In determining the stretch of amaterial web from the winding hardness, additional factors that distortthe result need to be taken into account. These factors which not onlyreproduce the “wound-in tensile stress”, also arise as a result of airwound in, or profile fluctuations, etc., such that the winding hardnessis not a sufficiently accurate measure of the stretch of a fibrous web.

SUMMARY OF THE INVENTION

The present invention provides a machine in which the stretch of thematerial web can be determined accurately.

According to the invention, a measuring device and at least onearrangement (or marking device) for applying at least two markings at adistance from one another in the longitudinal direction to the fibrousweb is fitted in the machine for measuring the distance between themarkings. In particular, a non-contact measuring device, arrangeddownstream of the arrangement in the web running direction of thefibrous web, is fitted in the machine for measuring the distance betweenthe markings.

The distance measured with the measuring device between the markings,for example following one another, is subsequently compared with theknown distance when setting the markings. In this manner, the stretch ofthe fibrous web is determined. It is possible during the comparison thatfurther measurements, such as the speed of the fibrous web or the webtension at specific points or the like, can be taken into account.

Furthermore, it should be noted that the marking is not restricted tobar symbols. The marking can include a code which comprises furtherinformation. For example, such information may include absolute valuesof the fibrous web length at the marking, or the type of paper, etc. Inthis case, the code can be formed as a numeric code or as a bar code.

According to the invention, the measuring system can be integrated in amachine at various points and may be used for various process steps. Forexample, in a winding machine, the stretch of the material web in theprocess chain (through which the latter runs) can also be determine whenarranged offline downstream of the machine for producing the fibrousweb. It is also possible to determine the wound-in tensile stressaccording to the invention. Further, a determination of the residualability to stretch the fibrous material before it breaks may be made,based on the measured stretch and the “stress” caused by this effect forthe fibrous material (or paper). This dependence can be presented in astress/strain graph. In connection with tensile measurements, statementsrelating to the modulus of elasticity of the fibrous material can bemade. These measurements can be verified with a soft sensor formeasuring strength properties in correlation with further datadetermined in a laboratory.

A soft sensor is understood to mean a software-based sensor in which rawmeasured data in the form of quality or process data are availableduring the production or finishing process. It is possible formeasurements of quality parameters in the laboratory to be incorporatedinto the raw measured data. Further, the raw measured data can becombined into data sets which have all been determined simultaneously.Further still, it is possible to select specific laboratory or qualitymeasurements as target data, which can be calculated from the other dataused as input data directed to at least one soft sensor algorithmrunning in a computer-based operation and combining unit. Each data setcontaining measured data which relates approximately to the sameinspection volume of web or raw material, in particular paper or paperfurnish.

According to another feature of the invention, the origin of windingdefects during the winding of the fibrous web to form a wound reel thatcan be analyzed. Further, the stretch measurements in conjunction withlength measurements can determine a measure of the “true length” of theweb wound up in a wound reel. Further still, markings on the fibrous websuch as on its outer edge can also be used in making a determination ofthe measurements.

According to another feature of the invention, a provision is made forthe arrangement to be arranged in a wire former or in a press section ofthe machine for producing the fibrous web. As a result, stretch of thefibrous web in the forming section or the press section could bedetermined with the method according to the invention.

According to another feature of the invention, there is at least onefurther measuring possibility for measuring the length of a section ofthe fibrous web in the machine. As a result, a marking applied to thefibrous web by the arrangement can be recalibrated, in order to achievea correlation between the marking and further length measuring devices.

According to another feature of the invention, another possibility ofmeasuring can be for non-contact measurements. For example, a rotaryencoder, a trigger device, a measuring device fitted to a roll, inparticular an encoder, or a device for measuring a drive signal.

According to another feature of the invention, the use of a comparisondevice for comparing the measured device measured by the measuringdevice and by the further measuring means. In particular, a controlcomputer may also be used. The data obtained by the non-contactmeasurement, includes the measurement of the web length (via rotaryencoders, triggers, etc. on rolls) and the measurement of the drivesignals at various points in the production process of the fibrous web.Further, the data obtained by the non-contact measurement can becompared with the original marking information to make a determinationof the web length.

Additionally, an evaluation unit can advantageously be used to evaluatethe measured values obtained by the comparison device, in particular thecontrol computer, relating to the stretch during the production of thefibrous web and to store or archive the data obtained.

The evaluation unit is advantageously connected to a further controlcomputer, which is arranged in an additional process unit, in particularalso operating offline in relation to the machine.

According to the invention, tension and stretch of the fibrous web areregistered independently of each other, so that the stretch can bedetected over the extensive course of a process.

The present invention is directed to a machine for a web comprising atleast one marking device structured and arranged to apply at least twomarkings at a distance from one another in a longitudinal direction tothe web. At least one measuring device is arranged downstream, relativeto a web run direction, of the at least one marking device, that isstructured and arranged to measure the distance between the markings.

In accordance with a feature of the invention, the machine is structuredand arranged to produce a fibrous web from a fibrous stock suspension.The machine is structured and arranged for one of finishing or furtherprocessing said fibrous web. Further, the fibrous web is one of a paper,board, or tissue web.

The at least one measuring device is a non-contact measuring device. Atleast one marking device is arranged in one of a wire former or in apress section of the machine. Further, at least one other measuringdevice is structured and arranged to measure a length of a section ofthe web in the machine. Further still, at least one other measuringdevice comprises one of a non-contact measuring device, a rotaryencoder, a trigger device, a measuring device fitted to a roll, anencoder, or a device for measuring a drive signal.

In accordance with a feature of the invention, a comparison devicecompares values measured by at least one measuring device and by atleast one other measuring device. Further, the comparison device can bea control unit. Further still, an evaluation unit is used to evaluatethe measured values and then compare them in the comparison device. Themeasured values correspond to a stretching of the web during production.Further, the evaluating unit stores the measured values. Further still,the evaluation unit can be either connected to a control unit orassigned to a process unit. The control unit is arranged in the processunit, which is arranged to operate offline from the machine. Further, atleast one measuring device is arranged to measure values relating to webstretch in at least one subsequent offline process. The at least onesubsequent offline process can be either calendering, coating, orwinding.

In accordance with a feature of the invention, a process for a webcomprises applying at least two markings on the web, which are separatedin a longitudinal direction of the web, and measures a distance betweenthe at least two markings. Further, the distance measuring occurs in aregion of a press section of a web production device. Further still, thedistance is measured without contacting the web and measures a length ofa section of the web in the machine.

In accordance with a feature of the invention, compares the distancemeasured and the measured length of the web section. Further, theprocess includes evaluating and storing values for the measured distanceand the measured length of the web section, which corresponds to astretching of the web.

In accordance with a feature of the invention, a machine for a webcomprising at least one arrangement for applying at least two markingsat a distance from one another in a longitudinal direction to the web.Further, at least one measuring device is arranged downstream of atleast one arrangement in a web running direction of the web, formeasuring the distance between the markings. Further still, at least onecontrol unit is used to control web stretching during the production ofthe web.

Other exemplary embodiments and advantages of the present invention maybe ascertained by reviewing the present disclosure and the accompanyingdrawing.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further described in the detailed descriptionwhich follows, in reference to the noted plurality of drawings by way ofnon-limiting examples of exemplary embodiments of the present invention,in which like reference numerals represent similar parts throughout theseveral views of the drawings, and wherein:

FIG. 1 shows a schematic drawing relating to the determination ofstretch by using a section of a machine for producing a fibrous web and

FIG. 2 shows a papermaking machine having devices for determining thestretch of the paper web.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The particulars shown herein are by way of example and for purposes ofillustrative discussion of the embodiments of the present invention onlyand are presented in the cause of providing what is believed to be themost useful and readily understood description of the principles andconceptual aspects of the present invention. In this regard, no attemptis made to show structural details of the present invention in moredetail than is necessary for the fundamental understanding of thepresent invention, the description taken with the drawings makingapparent to those skilled in the art how the several forms of thepresent invention may be embodied in practice.

FIG. 1 shows a machine for producing or treating a fibrous web 1comprises an arrangement of cylinders 2 to 8, over which or betweenwhich the fibrous web 1 is led. Between the cylinder 2 and the pair ofcylinders 3, 4 there is an arrangement (or marking device) 9 forapplying web edge markings to the fibrous web 1. Between the pair ofcylinders 3, 4 and a group of cylinders comprising the cylinders 5 to 8,there is arranged a device 10 for non-contact speed measurement of thefibrous web 1.

According to the invention a unit 12 for measuring the tension exertedon the fibrous web 1 is fitted on a roll 11. A rotary encoder 14 isinstalled on a further roll 13.

The arrangement (or marking device) 9 and the measuring devices 10, 12and 14 pass on their data to a control computer 15 (or control unit)that evaluates the data. In addition, a process unit 16 arranged offlinefrom the machine is equipped with measuring units 17, 18, 19 todetermine the distance between the markings on the fibrous web 1 and/orto calculate the rotational speed of rolls or cylinders, which passtheir data to a control computer 20 (or control unit). The latter, likethe control computer 15, is connected to an evaluation unit 21, in whichthe stretch of the fibrous web 1 in various method steps and atdifferent points in the process of its production is followed back andarchived.

FIG. 2 shows a papermaking machine equipped with for stretchmeasurements. In particular, a fibrous stock suspension from a head box22 is fed to a gap between two wires 23 and 24 of a twin-wire former 25.On the radius of a forming roll 26, the wires 23, 24 run toward eachother in a wedge shape and enclose the fibrous stock suspension betweenthem. In this case, first dewatering of the fibrous stock suspensiontakes place and a fiber mat is formed, from which a paper web 27 isproduced. An arrangement 28 for applying markings to the paper web 27,in particular to its web edge, is already present in the twin-wireformer 25.

The twin-wire former 25 is followed by a press section 29. The presssection 29 comprises, by way of example, as illustrated, three presslocations 30, 31, 32. The first two press locations 30, 31 form a tandemNipcoFlex press section, in which in each case a roll 33, 34 interactswith a shoe press roll 35, 36. In the region of the press section 29,there is for example a first measuring device 37 for measuring thedistance between the markings applied to the paper web 27 by thearrangement 28. However, it is noted that the first measuring device 37can alternatively be positioned between the presses 31 and 32 or may bepositioned before press 30. Moreover, it is contemplated that thearrangement 28 can be located in press section 29.

The press section 29 is followed by a drying section 40 havingdeflection rolls 38 and drying cylinders 39, in which the stretch of thepaper web 27 is likewise determined by a measuring device 41.

After the drying section 40, the paper web 27 is led through between ashoe roll 42 and a roll 43 of a shoe calender 44 used as a calenderingunit. The paper web 27 passes over deflection rolls into a film press 62having two film rolls 45, 46.

On each of the two film rolls 45, 46, an application nozzle 47 or 48applies a film of a coating color in excess, which is in each casedoctored off by a metering bar 49, 50. As a result of the wetting of thepaper web 27, its strength changes and the paper web 27 is stretched.Therefore, there can also be a measuring device 51 in the regiondownstream of the film press 62.

The paper web 27 is then led onward through a deflection element 52operating with air pressure to a float drier 53, such that the paper web27 is dried on both sides via thermal radiation or hot air anddownstream of which a measuring device 54 for measuring the stretch ofthe paper web 27 is may be installed.

The paper web 27, which is now dried again, is led onward over furtherdeflection rolls 55, 56 to a nozzle moistener 57, such that it isre-wetted again to a defined level of moisture and moisture gradient.Downstream of the nozzle moistener 57, the web 27 is calendered in acalender 58. The paper web 27 leaving the calender 58 is then wound upin a winding machine 59 to form a paper reel. The winding machine 59 forwinding the paper web 27 may also be arranged offline from the machinefor producing the paper web 27 from the fibrous stock suspension.Measuring devices 60 and 61 for measuring stretch are also arrangeddownstream of the nozzle moistener 57 and/or downstream of the calender58.

Likewise, rotary encoders for measuring the circumferential speed of theassociated rolls or cylinders can be built in, for example in rollsbelonging to the film press 62 or the calender 58. In particular, rotaryencoders would be able to determine the correlation between thecircumferential speed and the stretch and the slippage of the paper web27. All the data measured by the rotary encoders, the measuring devices37, 41, 51, 60, 61 and by other devices for measuring the speeds of thepaper web 27 and the rolls or cylinders are supplied to a controlcomputer (FIG. 1).

It is noted that the foregoing examples have been provided merely forthe purpose of explanation and are in no way to be construed as limitingof the present invention. While the present invention has been describedwith reference to an exemplary embodiment, it is understood that thewords which have been used herein are words of description andillustration, rather than words of limitation. Changes may be made,within the purview of the appended claims, as presently stated and asamended, without departing from the scope and spirit of the presentinvention in its aspects. Although the present invention has beendescribed herein with reference to particular means, materials andembodiments, the present invention is not intended to be limited to theparticulars disclosed herein; rather, the present invention extends toall functionally equivalent structures, methods and uses, such as arewithin the scope of the appended claims.

1. A machine for a web comprising: at least one marking devicestructured and arranged to apply at least two markings at a distancefrom one another in a longitudinal direction to the web; and at leastone measuring device arranged downstream, relative to a web rundirection, of said at least one marking device, structured and arrangedto measure the distance between the markings.
 2. The machine as claimedin claim 1, wherein the machine is structured and arranged to produce afibrous web from a fibrous stock suspension.
 3. The machine as claimedin claim 2, wherein the machine is structured and arranged for one offinishing or further processing said fibrous web.
 4. The machine asclaimed in claim 2, wherein the fibrous web is one of a paper, board, ortissue web.
 5. The machine as claimed in claim 1, wherein said at leastone measuring device is a non-contact measuring device.
 6. The machineas claimed in claim 1, wherein said at least one marking device isarranged in one of a wire former or in a press section of the machine.7. The machine as claimed in claim 1, further comprising at least oneother measuring device structured and arranged to measure a length of asection of the web in the machine.
 8. The machine as claimed in claim 7,wherein said at least one other measuring device comprises one of anon-contact measuring device, a rotary encoder, a trigger device, ameasuring device fitted to a roll, an encoder, or a device for measuringa drive signal.
 9. The machine as claimed in claim 1, further comprisinga comparison device for comparing values measured by said at least onemeasuring device and by said at least one other measuring device. 10.The machine as claimed in claim 9, wherein said comparison device is acontrol unit.
 11. The machine as claimed in claim 9, further comprisingan evaluation unit to evaluate the measured values compared in saidcomparison device, wherein the measured values correspond to astretching of the web during production.
 12. The machine as claimed inclaim 11, wherein said evaluating device stores the measured values. 13.The machine as claimed in claim 11, wherein said evaluation unit is oneof connected to a control unit or assigned to a process unit.
 14. Themachine as claimed in claim 13, wherein said control unit is arranged insaid process unit, which is arranged to operate offline from themachine.
 15. The machine as claimed in claim 11, wherein said at leastone measuring device is arranged to measure values relating to webstretch in at least one subsequent offline process.
 16. The machine asclaimed in claim 15, wherein said at least one subsequent offlineprocess is one of calendering, coating, or winding.
 17. A process for aweb comprising: applying at least two markings on the web, which areseparated in a longitudinal direction of the web; and measuring adistance between the at least two markings.
 18. The process inaccordance with claim 17, wherein the distance measuring occurs in aregion of a press section of a web production device.
 19. The process inaccordance with claim 17, wherein the distance is measured withoutcontacting the web.
 20. The process in accordance with claim 17, furthercomprising measuring a length of a section of the web in the machine.21. The process in accordance with claim 20, further comprisingcomparing the distance measured and the measured length of the websection.
 22. The process in accordance with claim 20, further comprisingevaluating and storing values for the measured distance and the measuredlength of the web section, which corresponds to a stretching of the web.23. A machine for a web comprising: at least one arrangement forapplying at least two markings at a distance from one another in alongitudinal direction to the web; at least one measuring devicearranged downstream of said at least one arrangement in a web runningdirection of the web for measuring the distance between the markings;and at least one control unit to control web stretching during theproduction of the web.